Their descendants are happy to just suck blood and pass along parasites to small mammals, but the hugeprehistoric fleas from 165 million years ago were equipped with saw-like projections around their mouth—for penetrating thick dino hides—that would probably make short work of a Chihuahua.

Thanks to well-preserved fossils recently discovered in China, scientists can now date fleas back to the Jurassic period, where the almost inch-long predators would have had to run down or ambush dinosaurs given they lacked the jumping abilities of today's pest. Which was fortunate for the past residents of our planet like the T-Rex, who obviously weren't well equipped for scratching. [Nature via MSNBC]